Need Help Choosing Software

Anti-virus: I recently decided that I was going to change from norton to a program that used less memory because of how much it slowed my computer. I did a little research, I used www.av-comparatives.org and www.virusbtn.com. From this data and a few user opinions I decided to try both kaspersky and nod32. Currently I'm running nod32 resident, and kasperky on-demand. I got the impression from users and tests that nod32 is better proactive but kaspersky has better overall detection. However, I'm not sure I want to have two anti-virus's installed. I kinda like to pick a "all in one" solution if you know what I mean and was leaning towards kaspersky because it is more user friendly and I think that matters too. I mean my mother would have no idea what to do with nod32 My question is should I leave both installed for the sake of security, or should I ditch one for the other?

Anti-Spyware:
I quit using ad-aware and spybot because their detection wasn't that great and of course because lavasoft was being sleazy. Instead I started using spy sweeper & Spwarewareblaster but just recently ran into problems with the latest 4.5 version of spy sweeper. It conflicts with spywareblaster and it takes a really long time to load at startup. It doesn't use too much memory but it uses enough. I have also been doubting the need for an active anti-spyware. Ever since using firefox w/ spywareblaster & being careful with the programs i download I havn't had 1 spyware infection. Here's some more questions for you...
Do you think there is a need for a active anti-spyware or should I just use it on-demand? Could you recommend some other anti-spyware apps? Does anyone know where I can find some tests of anti-spyware apps besides spywarewarrior (1 year old) and magazines (not very thorough).

Disk Defragmenters:

I was using Diskeeper Pro 9.0 but switched to perfectdisk after hearing that it's a better application. I don't care how long perfectdisk takes to defragment as long as it does a better job. I havn't been able to find many tests of defrag software. Has it been proven that perfectdisk has a better increase in performance over diskeeper?

Web Browsers:

I switched to mozilla firefox close to a year ago for security reasons and tabbed browsing. However firefox uses a lot of memory, starts off using a decent amount and then it skyrockets (I guess you would call that a memory leak). I am concerned about memory use as you can tell, I have a bit of an older computer. The only other web browser that I have considered is opera, but I don't like that fact that it comes with integrated irc and mail. Plus the interface is a little cluttered for my liking. I noticed that opera performs better in the acid2 test. What is the importance of this test in regards to choosing a web browser if any? Do you think i should switch to opera because it has better memory use?

Registry Cleaners:

Currently using ace utilites and I like it a lot. But I'm curious as to what other people suggest...
Can you recommend me a program and point me to some comparitive tests?

Thanks alot,
Secure5150

P.S. If theres anything else I should be doing for security or performance let me know.